ATT Bulk Density, Voids & Organic Impurities 3 — Questions and Answers
Question 1: Which ASTM standard governs the Organic Impurities in Fine Aggregates for Concrete test?
- ASTM C29
- ASTM C33
- ASTM C40 (Correct answer)
- ASTM C127
Correct answer: ASTM C40
ASTM C40 is the standard test method for organic impurities in fine aggregates for concrete.
Question 2: In the ASTM C29 jigging method, how many times is each side of the measure raised and dropped per layer?
- 25 times
- 50 times (Correct answer)
- 75 times
- 100 times
Correct answer: 50 times
The jigging method requires each side of the measure to be raised approximately 50 mm (2 in) and dropped 50 times per layer.
Question 3: If the liquid color in an ASTM C40 test is lighter than the reference standard, what does this indicate?
- The aggregate contains excessive organic impurities
- The NaOH solution must be replaced
- The aggregate likely has acceptable organic impurity levels (Correct answer)
- The test is invalid and must be repeated
Correct answer: The aggregate likely has acceptable organic impurity levels
A color lighter than Organic Plate No. 3 indicates the fine aggregate likely does not contain harmful levels of organic impurities.
Question 4: The reference color in the ASTM C40 organic impurities test is equivalent to Gardner Color Standard No.:
- 5
- 8
- 11 (Correct answer)
- 15
Correct answer: 11
Organic Plate No. 3 (the reference standard for ASTM C40) is equivalent to Gardner Color Standard No. 11.
Question 5: What is the diameter of the tamping rod specified in ASTM C29?
- 10 mm (3/8 in)
- 16 mm (5/8 in) (Correct answer)
- 20 mm (3/4 in)
- 25 mm (1 in)
Correct answer: 16 mm (5/8 in)
ASTM C29 specifies a smooth, straight steel tamping rod 16 mm (5/8 in) in diameter and approximately 600 mm (24 in) in length.
Question 6: The jigging method in ASTM C29 is appropriate for aggregates with maximum particle sizes between:
- 3/4 in (19 mm) and 1-1/2 in (37.5 mm)
- 1 in (25 mm) and 2 in (50 mm)
- 1-1/2 in (37.5 mm) and 3 in (75 mm) (Correct answer)
- 2 in (50 mm) and 4 in (100 mm)
Correct answer: 1-1/2 in (37.5 mm) and 3 in (75 mm)
The jigging method is used for aggregates with maximum particle sizes greater than 37.5 mm (1-1/2 in) and up to 75 mm (3 in).
Question 7: What shape is the working end of the tamping rod specified in ASTM C29?
- Pointed
- Square
- Hemispherical (Correct answer)
- Flat and chisel-shaped
Correct answer: Hemispherical
ASTM C29 requires one end of the tamping rod to be hemispherical in shape to prevent breaking aggregate particles during compaction.
ATT Bulk Density, Voids & Organic Impurities 3
Which ASTM standard governs the Organic Impurities in Fine Aggregates for Concrete test?